The invention relates to a seal for a rolling bearing unit consisting of an inner race and an outer race, becoming or forming a unit with an attaching flange, and rows of rolling members between the races.
A rolling bearing unit of the type mentioned, wherein seals pursuant to the invention are used, is a rolling bearing fully adjusted and lubricated in advance, which may be used directly as such, in particular for the bearing system of the front wheels of a motor vehicle with four-wheel drive.
It is self-evident that in such a rolling bearing unit heavy demands are placed on the seals, since on no account should dirt be able to penetrate into the rolling bearing from outside and, furthermore, the lubricant should not be able to leak out of the bearing. In addition, such a rolling bearing, when used as a wheel bearing for a motor vehicle with four-wheel drive, is subject to extra stresses arising as a result of turning and rotation of the wheels during steering and driving, as well as owing to motive forces. Taking this into account, the seals must be completely yielding at one edge but at the other edge must retain their sealing ability under all circumstances.
Hitherto such seals have comprised an annular member with one or a plurality of springy lips which rest against the inner race, such as shown, for example, in U.S. Pat. No. 4040683.
It has appeared, however, that such seals with springy lips fail to produce effective long-lasting sealing of a rolling bearing of the type mentioned, in particular owing to the aforementioned extra stresses arising during use or to other circumstances, such as relatively high operating temperatures.